OLYMPIA, Wash. Aug 14 (Reuters) - Firefighters in
Washington state fought a wildfire on Tuesday that has destroyed
60 homes and burned more than 20,000 acres (8,093 hectares)
between two national forests east of the capital, Olympia.

Another 400 homes were evacuated in the rolling hills
between Cle Elum and Ellensburg, two towns in northwest
Washington at the eastern edge of the Cascade Mountains.

The massive blaze was among more than a dozen wildfires
burning across the U.S. West, which is wilting under a heat wave
that has sent temperatures into the triple digits. Together, the
fires have singed around 230,000 acres (93,000 hectares) across
Idaho, Washington and California.

Authorities suspect the Washington state fire began at a
construction site east of Cle Elum, about 75 miles (120
km)southeast of Seattle.

"We don't know the cause, we just know the origin," said
Rick Scriven, a spokesman for a state emergency response team at
the scene.

With strong winds expected to pick up Tuesday afternoon and
no rain in the area for three weeks, more damage is likely, said
Bryan Flint, spokesman for the Department of Natural Resources.

The fire is likely to spread to the north, where it could
reach the Wenatchee National Forest within 10 miles (16 km), and
to the east, which is mostly farmland, Flint said. South of the
fire is the Snoqualmie National Forest.

"It's going to be a changing situation all day long," Flint
said. "This fire is by no means over with."

In Northern California, more than 1,100 firefighters spent a
third day attacking a pair of wildfires that have destroyed two
homes in Lake County's Spring Valley area and charred some 7,000
acres (2,832 hectares).

Daniel Berlant, a California Department of Forestry and Fire
Protection spokesman, said firefighters had contained only 30
percent of the two blazes burning dry brush in remote Lake and
Colusa counties and did not expect full containment for a week.

But firefighters made enough progress attacking one of the
fires that authorities lifted an evacuation order for 480 homes
in the Spring Valley area on Monday night, he added.

Berlant said the fires had moved east into Colusa County and
continued to threaten the area around Wilbur Hot Springs, a
resort that offers clothing-optional bathing in mineral water.
The resort closed on Sunday for 12 days of maintenance and it
was not clear if anyone had been forced to flee.

'CATASTROPHE'

Two firefighters suffered minor injuries while working the
blaze in triple-digit temperatures. Berlant said California had
experienced a significant increase in fires this year.

Suzann Thompson, who works the front desk at Clear Lake
Cottages and Marina in Clearlake, said the fires decimated
business throughout the area. Clear Lake, the biggest lake in
California, is a popular tourist attraction.

"It's really a catastrophe," she said.

In Idaho, fire crews struggled to contain a dozen blazes
raging across more than 200,000 acres (80,937 hectares) of
steep, forested terrain. A 20-year-old U.S. Forest Service
firefighter was killed in Idaho on Sunday when a tree fell on
her, U.S. Forest Service spokeswoman Elizabeth Slown said.

Smoke and ash pouring into communities from the state
capital of Boise to the ranching community of Salmon in east
central Idaho caused health officials to caution against undue
exertion outdoors because of poor air quality.

Robyn Broyles, spokeswoman for the National Interagency Fire
Center in Boise, said several blazes in Idaho's mountains were
far from contained and likely would not be extinguished "until
the snow flies."

Wildfires have consumed roughly 6 million acres across the
nation this year. That compares to the 10-year average of 4.9
million acres, according to figures from the interagency fire
center.
(Additional reporting by Ronnie Cohen, Laura Zuckerman and Dan
Whitcomb; Editing by Stacey Joyce; Writing by Dan Whitcomb)